Conventionally, an image stabilizing function against image shake due to hand movement or the like has become indispensable in image pickup systems such as video cameras, and various types of image stabilizing optical systems have been proposed.
For example, as disclosed in JP H08-29737A, a type is known in which an optical system for image stabilization configured by two lenses is mounted in front of a zoom lens and stabilizes image shake by moving one of these lenses perpendicularly with respect to the optical axis.
Moreover, as disclosed in JP H07-128619A, a type is known in which, in a zoom lens made of four lens units, image shake due to hand movement is stabilized by moving a part of the third lens unit constituted by a plurality of lenses perpendicularly with respect to the optical axis.
However, in the type disclosed in JP H08-29737A, the optical system for image stabilization is mounted in front of the zoom lens, so that the lens diameter of the optical system for image stabilization becomes large. Moreover, the overall device becomes accordingly large, thus increasing the load on the driving system. For this reason, it was disadvantageous with regard to miniaturization, lighter weight and energy saving.
In the type disclosed in JP H07-128619A, in order to stabilize an image against image shake, a part of the three units fixed with respect to the image plane is perpendicularly movable with respect to the optical axis, so that it is advantageous with regard to size compared to the type in which the optical system for image stabilization is mounted in front of the zoom lens. However, the lens unit for image stabilization is made of three lenses, so that the load on the actuator is large, and also the zoom ratio is smaller than a factor of about ×10.